- Email: [email protected]
Morphometric analysis of renal arteries in patients with renal cell carcinoma,
ARTICLE IN PRESS
Pathology – Research and Practice 203 (2007) 647–652 www.elsevier.de/prp
ORIGINAL ARTICLE
Morphometric analysis of renal arteries in patients with renal cell carcinoma,$, $$ Karla Tomica,, Domagoj Mladinovb, Lovorka Batelja-Vuleticc, Borislav Spajicd, August Mijice, Davor Tomasb, Mladen Beliczab, Bozo Kruslinb a
Department of Pathology, Josip Bencevic General Hospital, Andrije Stampara 42, 35000, Slavonski Brod, Croatia Ljudevit Jurak University Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia c Department of Pathology, School of Medicine, University of Zagreb, Zagreb, Croatia d University Department of Urology, Sestre milosrdnice University Hospital, Zagreb, Croatia e University Department of Surgery, Sestre milosrdnice University Hospital, Zagreb, Croatia b
Received 22 March 2007; accepted 8 June 2007
Abstract The aim of this study was to analyze morphometric parameters of renal arteries (longest diameter and tunica media thickness) in patients with renal cell carcinoma (RCC), to look into their relationship to tumor necrosis and to compare them with morphometric parameters recorded in a control group. We analyzed archival cases of RCC diagnosed in 2003 that also contained routinely sampled specimens of distal segments of renal artery. The control group consisted of specimens from both renal arteries obtained from 16 patients at routine autopsy during 2004–2005. Autopsy, as well as further histological analysis, did not disclose any malignant disease in the control group. Morphometric analysis of diameter and thickness of the renal artery tunica media was performed using Issa 3.1 software (Vamstek 2002, Zagreb, Croatia). The comparison of tunica media thickness showed that renal arteries from RCC cases were significantly thicker compared to distal parts of renal arteries in the control group (p ¼ 0.0002). Although renal artery samples from cases with necrotic tumor areas were thicker than those without tumor necrosis, the difference was not statistically significant. It is concluded that significantly thicker tunica media characterizes renal arteries in the group of patients with RCC when compared with the control group. r 2007 Elsevier GmbH. All rights reserved. Keywords: Renal artery; Renal cell carcinoma; Tunica media; Atherosclerosis; Fibromuscular dysplasia
Introduction $ The study was accomplished at Ljudevit Jurak University Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia. $$ Presented in part at the 20th European Congress of Pathology, Paris, France, September 3–8, 2005. Corresponding author. Tel.: 00385 35 201 900. E-mail address: [email protected] (K. Tomic).
0344-0338/$ - see front matter r 2007 Elsevier GmbH. All rights reserved. doi:10.1016/j.prp.2007.06.005
Renal cell carcinoma (RCC) accounts for 1–3% of all human cancers, and over 90% of malignant renal tumors affect adults. It is 2–3 times more common in men, and the average age at diagnosis is 55–60 years [3,15]. Tobacco smoking, obesity, and hypertension are considered the most important risk factors [1,3].
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Although hypertension is a well-known risk factor in patients with RCC, it can also represent a paraneoplastic symptom of the tumor itself [7]. The major prognostic factors for the outcome of RCC patients are tumor size, histological type, nuclear grade, stage of disease, and metastatic dissemination [2]. Recently, the presence and extent of tumor necrosis have also been considered a predictor of more aggressive tumor behavior and poorer prognosis [6,17]. The majority of authors suggest that decreased tumor microvessel density leads to chronic hypoxia of the tumor tissue, which then causes coagulative necrosis [10,17]. However, some authors suggest that pathologic changes in renal arteries could also be responsible for tumor necrosis in RCC [11,20]. Different lesions, most frequently atherosclerosis, and, less commonly, fibromuscular dysplasia (FMD) or some other conditions such as Takayasu arteritis, radiation injury, and congenital malformations [15] may affect the main renal artery. Atherosclerosis is a generalized progressive arterial disease associated with localized arterial occlusions that accounts for 90% of cases of renal artery stenosis. It usually involves the ostium and the proximal third of the main renal artery and perirenal aorta [15,16]. Arterial FMD is a non-inflammatory, nonatherosclerotic, occlusive condition of systemic arteries with predilection for renal and internal carotid arteries [19]. FMD of renal arteries is bilateral in nearly half of the patients, and more common on the right side (3:1); it is usually diagnosed in the fourth decade, is predominant in females, and most frequently affects the distal two thirds of the renal artery and its branches [15,16]. The exact incidence of FMD is not known due to a large number of asymptomatic cases; however, an autopsy study showed an incidence of 1% [9,12]. Intimal, medial, and adventitial FMD are three major pathologic subtypes of FMD. Although RCC is connected to hypertension and there are some suggestions that renal artery changes could be responsible for tumor necrosis in patients with RCC, the exact nature of this relationship is not fully understood. The aim of this study was to analyze morphometric parameters of renal arteries (longest diameter and thickness of arterial tunica media) in patients with RCC, to compare them with those of a control group of patients without RCC, and to gain additional, more objective information about the relationship between RCC and renal arteries.
Materials and methods We analyzed archival cases of RCC diagnosed at Ljudevit Jurak University, Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia,
in 2003. For these cases samples of renal arteries were also available. Of the consecutive series of 61 (M:F ¼ 38:23) cases, 21 (14 male and 8 female) cases were excluded because of the tangentially cut or artificially damaged renal artery specimens, especially in cases of right simple nephrectomy, when renal artery is cut at a length of 50–75%. The final sample consisted of 39 (M:F ¼ 24:15) RCC cases, patient age 35–74 years (mean 58.4 years). Tumor size ranged from 2–16 cm (mean 7.37 cm). All cases included in the study contained routinely sampled specimens of distal segments of renal artery, as well as renal vein and ureteral margin. The presence and extent of tumor necrosis were characterized using the degrees absent, less than 50% tumor necrosis, and using the degrees more than 50% tumor necrosis, as in similar studies of RCC [11] and studies of soft tissue-tumor grading [21]. The control group consisted of specimens from both renal arteries obtained during the 2004–2005 period from 16 (M:F ¼ 11:5) patients aged 32–85 years (mean 62.3 years) on routine autopsy at Ljudevit Jurak University, Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia. Autopsy, as well as further histological analysis, did not disclose any malignant disease in the control group, and causes of death were non-tumor diseases (heart failure, pneumonia, and pulmonary thromboembolism). Measurements of renal arteries in the control group were performed on sections from 32 renal arteries. One block each from the distal and proximal parts was morphometrically analysed in all 32 renal arteries. FMD was classified into three principal pathological types: intimal, medial, and adventitial FMD [12]. Medial type (type II) was subdivided into three subtypes: medial ‘‘muscular’’ hyperplasia (type IIa), medial fibroplasia with aneurysms (type IIb), and perimedial fibroplasia (type IIc) [4,13,19,23]. Specimens from both groups of patients were equally processed; first routinely fixed in 10% buffered formaldehyde, embedded in paraffin, cut at 5 mm and stained with hematoxylin–eosin and orcein, and examined by light microscopy. Morphometric analysis of the longest diameter and thickness of renal artery tunica media on adequate sections was performed using a JVC TK-1270 video camera, Leica Diaplan microscope and Issa 3.1 computer software (Vamstek 2002, Zagreb, Croatia). The longest diameter was measured from adventitia to adventitia, and thickness of tunica media from elastica interna to elastica externa, using slides stained with orcein (Fig. 1A and B). In the group of patients with RCC, one bloc per case was evaluated, because after nephrectomy, only short distal segment of renal artery was available for histologic analysis. In both groups, we used 3 measurements per case and then counted the mean value.
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Fig. 1. Morphometric analysis of renal artery: (A) longest diameter, magnification 25; (B) thickness of tunica media, magnification 40; both microphotographs for morphometric analysis were stained with orcein.
Mann–Whitney U test was used for statistical analysis. The level of significance was set at po0.05.
Results In the study of 39 RCC cases, there were 24 (61.5%) male patients aged 38–74 years (mean 57.2 years) and 15 (38.5%) female patients aged 35–74 years (mean 53.6 years). Pathologic changes of renal arteries were found in 24 renal artery sections (M:F ¼ 12:12), whereas 15 (M:F ¼ 11:4) cases were free of pathologic changes of renal artery samples. Out of 24 cases with renal artery changes, renal artery atherosclerosis was recorded in 6 (M:F ¼ 4:2), and FMD in 18 (M:F ¼ 8:10) cases (Fig. 2A–C). Results of morphometric measurements of renal artery longest diameter and of tunica media thickness in the group of RCC patients are shown in Table 1. Statistical analysis yielded no significant differences in the longest diameter of renal artery or media layer thickness between the patients with (FMD or atherosclerosis) and without renal artery lesions (p ¼ 0.885 for diameter and p ¼ 0.828 for media thickness, p ¼ 0.213 for longest diameter and p ¼ 0.087 for media thickness). The comparison of cases with FMD and atherosclerotic changes in renal artery yielded no significant difference either (p ¼ 0.205 for longest diameter and p ¼ 0.096 for tunica media thickness). Tumor necrosis was found in 31 (79.5%) RCC cases, and of these, 23 (M:F ¼ 15:8) had less than 50% necrosis, and 8 (M:F ¼ 4:4) more than 50% of necrotic areas. Sections of renal arteries without tumor necrosis had a median diameter of 3492.27 mm (range 2757.30– 3852.82 mm) and a media thickness of 499.41 mm (range 353.37–643.03 mm). The median diameter of renal arteries with less than 50% of necrotic areas was
3448.18 mm (range 837.30–5248.28 mm), and tunica media thickness in these was 531.37 mm (range167.86–1153.30 mm). The median diameter of renal arteries with tumors containing more than 50% of necrotic areas was 4233.75 mm (range 2377.35– 5180.04 mm), with thickness of tunica media measuring 657.32 mm (range 365.45–969.52 mm). The comparison of diameter and thickness of tunica media of renal arteries from cases without necrosis with those with necrotic areas and between cases with different degrees of tumor necrosis produced no statistically significant differences (p40.05). In the control group, pathologic changes of renal arteries were found on 17 (53.1%) sections from proximal parts of renal arteries and on only 6 (18.8%) sections from distal segments of renal arteries. All changes observed on both distal and proximal sections were atherosclerotic, whereas FMD was not found at all. Measurements of distal and proximal sections in the control group are presented in Tables 2 and 3. Statistical analysis revealed no significant gender differences in renal artery diameter and tunica media thickness in either distal or proximal segments of renal arteries (p40.05). Within the control group, the comparison of renal artery diameter and tunica media thickness between sections without lesions and those with atherosclerosis yielded no statistical significance for either distal or proximal segments (p40.05). The longest diameter of distal segments of renal arteries in the control group was slightly wider when compared with renal arteries with RCC, but the difference did not reach statistical significance (p40.05). However, the comparison of tunica media thickness showed renal arteries from RCC cases to be significantly thicker when compared with distal segments of renal arteries in the control group (p ¼ 0.0002). The comparison of tunica media thickness between
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Fig. 2. (A) Macroscopic appearance of renal cell carcinoma with atherosclerotic lesions of renal artery, (B) microphotograph of a renal artery with fibromuscular dysplasia IIb, (C) microphotograph of a renal artery with atherosclerotic lesions; microphotographs were stained with hematoxylin and eosin, magnification 40.
Table 1. Median, minimum, and maximum values of measured parameters on renal arteries from cases with renal cell carcinoma
Table 2. Median, minimum, and maximum values of measured parameters on distal parts of renal arteries from control group
Median (mm)
Minimum (mm)
Median (mm)
3783.82 3808.79
837.30 859.95
5248.28 5203.66
3407.20 4154.71
837.30 3197.46
5214.47 5248.28
All
531.37
167.86
1153.30
No changes FMD ATH
503.61
167.86
969.52
529.34 622.63
353.37 520.73
1153.30 835.70
Diameter
Media layer thickness
All No changes FMD ATH
Maximum (mm)
All ¼ all cases with renal cell carcinoma; No changes ¼ cases of renal cell carcinoma without renal artery changes; FMD ¼ cases of renal cell carcinoma with fibromuscular dysplasia of renal arteries; ATH ¼ cases of renal cell carcinoma with atherosclerosis of renal arteries.
renal artery sections with atherosclerosis from the RCC group (median 622.63 mm) and distal sections with atherosclerosis from the control group (median 434.37 mm) yielded a statistically significant difference
Diameter
Media layer thickness
All 4109.88 No 4068.42 changes ATH 4237.82
Minimum (mm)
Maximum (mm)
2386.33 2386.33
7304.33 7304.33
3723.11
4821.75
All
386.30
171.19
651.28
No changes ATH
363.89
171.19
651.28
434.37
266.22
547.84
All ¼ all sections from distal segments of renal arteries; No changes ¼ sections from distal parts of renal arteries without pathological changes; ATH ¼ sections from distal parts of renal arteries with atherosclerotic lesions of renal arteries.
(p ¼ 0.019). A statistically significant difference was also found when tunica media thickness of sections without pathologic changes on renal arteries from the RCC group was compared with sections of distal parts without pathologic changes in the control group (p ¼ 0.010).
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Table 3. Median, minimum, and maximum values of measured parameters on proximal parts of renal arteries from control group Median (mm) Diameter
Media layer thickness
All 4999.14 No 4940.09 changes ATH 5052.17
Minimum (mm)
Maximum (mm)
2506.33 2765.93
9045.64 6757.04
2506.33
9045.64
All
368.22
138.31
721.66
No changes ATH
328.66
214.77
522.95
407.77
138.31
721.66
All ¼ all sections from proximal segments of renal arteries; No changes ¼ sections from proximal parts of renal arteries without pathological changes; ATH ¼ sections from proximal parts of renal arteries with atherosclerotic lesions of renal arteries.
Discussion Although both the present and previous studies [11,20] point to a high rate of renal artery lesions in RCC patients, we found no significant differences in renal artery diameter or media layer thickness between renal arteries without changes and those with FMD or atherosclerotic lesions. This finding was not unexpected since our study of the control group, as well as other studies [4,12,16,19], showed renal artery changes to be mostly segmental, with only a small part of renal artery being available for sampling and histological examination after radical nephrectomy due to RCC. However, when renal artery sections from the group of RCC patients were compared with distal segments of renal arteries from the control group, we found that tunica media was significantly thicker in the group of RCC patients. The difference in media layer thickness was also present when only sections with atherosclerosis from both groups were compared, as well as on comparison of sections without pathologic changes. These results suggest that renal arteries in RCC patients are changed, with a thicker tunica media that can narrow arterial lumina and influence arterial blood flow. According to some authors, necrosis in RCC is attributed to a decrease in microvessel density and immaturity of microvessels with the possibility that tumor necrosis is a consequence of acute hypoxia [10,17]. However, the exact pathogenesis of tumor necrosis as well as the cause and nature of renal artery changes, and the possible impact on tumor necrosis have not yet been fully clarified [11,17]. We observed an increase in media layer thickness in the group of RCC patients, with the presence and increased extent of
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tumor necrosis (no necrosis: less than 50% necrosis: more than 50% necrosis ¼ 499.4 mm, 531.4 mm, 657.3 mm); however, the differences were not statistically significant. Concerning a relatively small number of cases without tumor necrosis and a small number of cases with more than 50% tumor necrosis in the present study, the hypothesis that renal artery changes induce necrosis or influence the extent of tumor necrosis should be further analyzed (in larger series and in comparison with microvessel density). In the hypertensive population, high blood pressure is attributed mainly to atherosclerosis, whereas renovascular FMD is considered to be the cause of hypertension in less than 2% of patients [23]. In patients with renovascular hypertension, FMD is the underlying cause in 20%–50% of cases [12]. Hypertension has been implicated as a risk factor for the development of RCC, and also as a paraneoplastic manifestation of RCC [1,7,18]. Hypertension has also been implicated as a risk factor for increased mortality from RCC [5,8]. Due to the asymptomatic nature in a large number of cases and inadequately sensitive imaging methods, the true incidence and prevalence of FMD in the general, healthy population and in patients with hypertension or RCC remain unknown. The best method for detecting renal artery stenosis is digital subtraction angiography; however, the use of this method in daily routine is very rare, in particular in patients with renal tumor [14,22]. Based on our results, we may conclude that significantly thicker tunica media characterized renal arteries in the group of patients with RCC when compared with the control group, without any significant difference between arteries with and without pathologic changes. These findings suggest that renal arteries in all patients with RCC are changed, but since distribution of FMD and atherosclerosis could be only segmental, their presence may not be identified in all cases because whole renal artery is not available for pathologic examination due to operative techniques. Yet, it remains unknown whether they are the consequence of tumor or represent a risk factor for hypertension or even tumor growth. The morphometric results of our study encourage further studies to elucidate the cause of the high rate of renal artery lesions and the association of these lesions with the development and extent of tumor necrosis, as well as the exact relationship of the hypertension and RCC.
References [1] W.H. Chow, G. Gridley, J.F. Fraumeni, B. Ja¨rvholm, Obesity, hypertension, and the risk of kidney cancer in men, N. Engl. J. Med. 343 (2000) 1305–1311. [2] H.T. Cohen, F.J. McGovern, Renal cell carcinoma, N. Engl. J. Med. 353 (2005) 2477–2490.
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[3] J.N. Eble, K. Togashi, P. Pisani, Renal cell carcinoma, in: J.N. Eble, G. Sauter, J.I. Epstein, I.A. Sesterhenn (Eds.), Tumors of the Urinary System and Male Genital Organs: World Health Organization Classification of Tumors, IARC Press, Lyon, 2004, pp. 12–14. [4] A.Z. Fenves, V.S. Ram, Fibromuscular dysplasia of the renal arteries, Curr. Hypertens. Rep. 1 (1999) 546–549. [5] A.E. Fletcher, D.G. Beevers, C.J. Bulpitt, E.C. Coles, C.T. Dollery, J.G. Ledingham, A.J. Palmer, J.C. Petrie, J. Webster, Cancer mortality and atenolol treatment, Br. Med. J. 306 (1993) 622–623. [6] I. Frank, M.L. Blute, J.C. Cheville, C.M. Lohse, A.L. Weaver, H. Zincke, An outcome prediction model for patients with clear cell renal cell carcinoma treated with radical nephrectomy used on tumor stage, size, grade and necrosis: the SSIGN score, J. Urol. 168 (2002) 2395–2400. [7] P.J. Gold, A. Fefer, J.A. Thompson, Paraneoplastic manifestations of renal cell carcinoma, Semin. Urol. Oncol. 14 (1996) 216–222. [8] E. Grossman, F.H. Messerli, V. Boyko, U. Goldbourt, Is there an association between hypertension and cancer mortality?, Am. J. Med. 112 (2002) 479–486. [9] M.J. Heffelinger, K.E. Holley, E.G. Harrison JR, J.C. Hunt, Arterial fibromuscular dysplasia studied at autopsy, Am. J. Clin. Pathol. 54 (1970) 274. [10] B. Hemmerlein, A. Kugler, R. Olisik, R.H. Ringert, H.J. Radzun, P. Thelen, Vascular endothelial growth factor expression, angiogenesis, and necrosis in renal cell carcinomas, Virchows Arch. 439 (2001) 645–652. [11] B. Kruslin, K. Tomic, D. Tomas, D. Mladinov, D. Trnski, M. Belicza, The correlation between the tumor necrosis and renal artery changes in renal cell carcinoma, Int. J. Surg. Pathol. 14 (2006) 312–319. [12] T.F. Luscher, J.T. Lie, A.W. Stanson, O.W. Houser, L.H. Hollier, S.G. Sheps, Arterial fibromuscular dysplasia, Mayo Clin. Proc. 62 (1987) 931–952. [13] V. Nickeleit, S. Moll, E. Cynke, F.P. Brunner, M. Michatsch, A young woman with high blood pressure on haemodialysis: it is never too late to evaluate hypertension, Nephrol. Dial. Transplant. 14 (1999) 2734–2737.
[14] R. Parasuraman, N. Attallah, K.K. Venkat, A. Yoshida, M. Abouljoud, S. Khanal, A. Greenbaum, Rapid progression of native renal artery fibromuscular dysplasia following kidney donation, Am. J. Transplant. 4 (2004) 1910–1914. [15] J. Rosai, Rosai and Ackerman’s Surgical Pathology, Mosby, St. Louis, MO, 2004. [16] R.D. Safian, S.C. Textor, Renal artery stenosis, N. Engl. J. Med. 344 (2001) 431–442. [17] S. Sengupta, C.M. Lohse, B.C. Leibovitz, I. Frank, R.H. Thompson, W.S. Webster, H. Zincke, M.L. Blute, J.C. Cheville, E.D. Kwon, Histologic coagulative tumor necrosis as a prognostic indicator of renal cell carcinoma aggressiveness, Cancer 104 (2005) 511–520. [18] J.A. Shapiro, M.A. Williams, N.S. Weiss, A. Stergachis, A.Z. LaCroix, W.E. Barlow, Hypertension, antihypertensive medication use and risk of renal cell carcinoma, Am. J. Epidemiol. 149 (1999) 521–530. [19] J.C. Stanley, B.L. Gewertz, E.L. Bove, V. Sottiurai, W.J. Fry, Arterial fibrodysplasia. Histopathologic character and current etiologic concepts, Arch. Surg. 110 (1975) 561–566. [20] K. Tomic, D. Tomas, I. Tomaskovic, M. Kos, M. Belicza, B. Kruslin, Renal artery changes in patients with primary renal cell carcinoma, Virchows Arch. 448 (2006) 24–28. [21] M. Trojani, G. Contesso, J.M. Coindre, J. Rouesse, N.B. Bui, A. de Mascarel, J.F. Goussot, M. David, F. Bonichon, C. Lagarde, Soft-tissue sarcomas of adults; study of pathological prognostic variables and definition of a histopathological grading system, Int. J. Cancer 33 (1984) 37–42. [22] G.B. Vasbinder, P.J. Nelemans, A.G. Kessels, A.A. Kroon, J.H. Maki, T. Leiner, F.J. Beek, M.B. Korst, K. Flobbe, M.W. de Haan, W.H. van Zwam, C.T. Postma, M.G. Hunink, P.W. de Leeuw, J.M. van Engelshoven, Accuracy of tomographic angiography and magnetic resonance angiography for diagnosing renal artery stenosis, Ann. Intern. Med. 141 (2004) 674–682. [23] S.P. Youngberg, S.G. Sheps, C.G. Strong, Fibromuscular disease of the renal arteries, Med. Clin. N. Am. 61 (1977) 623–641.
Pathology – Research and Practice 203 (2007) 647–652 www.elsevier.de/prp
ORIGINAL ARTICLE
Morphometric analysis of renal arteries in patients with renal cell carcinoma,$, $$ Karla Tomica,, Domagoj Mladinovb, Lovorka Batelja-Vuleticc, Borislav Spajicd, August Mijice, Davor Tomasb, Mladen Beliczab, Bozo Kruslinb a
Department of Pathology, Josip Bencevic General Hospital, Andrije Stampara 42, 35000, Slavonski Brod, Croatia Ljudevit Jurak University Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia c Department of Pathology, School of Medicine, University of Zagreb, Zagreb, Croatia d University Department of Urology, Sestre milosrdnice University Hospital, Zagreb, Croatia e University Department of Surgery, Sestre milosrdnice University Hospital, Zagreb, Croatia b
Received 22 March 2007; accepted 8 June 2007
Abstract The aim of this study was to analyze morphometric parameters of renal arteries (longest diameter and tunica media thickness) in patients with renal cell carcinoma (RCC), to look into their relationship to tumor necrosis and to compare them with morphometric parameters recorded in a control group. We analyzed archival cases of RCC diagnosed in 2003 that also contained routinely sampled specimens of distal segments of renal artery. The control group consisted of specimens from both renal arteries obtained from 16 patients at routine autopsy during 2004–2005. Autopsy, as well as further histological analysis, did not disclose any malignant disease in the control group. Morphometric analysis of diameter and thickness of the renal artery tunica media was performed using Issa 3.1 software (Vamstek 2002, Zagreb, Croatia). The comparison of tunica media thickness showed that renal arteries from RCC cases were significantly thicker compared to distal parts of renal arteries in the control group (p ¼ 0.0002). Although renal artery samples from cases with necrotic tumor areas were thicker than those without tumor necrosis, the difference was not statistically significant. It is concluded that significantly thicker tunica media characterizes renal arteries in the group of patients with RCC when compared with the control group. r 2007 Elsevier GmbH. All rights reserved. Keywords: Renal artery; Renal cell carcinoma; Tunica media; Atherosclerosis; Fibromuscular dysplasia
Introduction $ The study was accomplished at Ljudevit Jurak University Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia. $$ Presented in part at the 20th European Congress of Pathology, Paris, France, September 3–8, 2005. Corresponding author. Tel.: 00385 35 201 900. E-mail address: [email protected] (K. Tomic).
0344-0338/$ - see front matter r 2007 Elsevier GmbH. All rights reserved. doi:10.1016/j.prp.2007.06.005
Renal cell carcinoma (RCC) accounts for 1–3% of all human cancers, and over 90% of malignant renal tumors affect adults. It is 2–3 times more common in men, and the average age at diagnosis is 55–60 years [3,15]. Tobacco smoking, obesity, and hypertension are considered the most important risk factors [1,3].
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Although hypertension is a well-known risk factor in patients with RCC, it can also represent a paraneoplastic symptom of the tumor itself [7]. The major prognostic factors for the outcome of RCC patients are tumor size, histological type, nuclear grade, stage of disease, and metastatic dissemination [2]. Recently, the presence and extent of tumor necrosis have also been considered a predictor of more aggressive tumor behavior and poorer prognosis [6,17]. The majority of authors suggest that decreased tumor microvessel density leads to chronic hypoxia of the tumor tissue, which then causes coagulative necrosis [10,17]. However, some authors suggest that pathologic changes in renal arteries could also be responsible for tumor necrosis in RCC [11,20]. Different lesions, most frequently atherosclerosis, and, less commonly, fibromuscular dysplasia (FMD) or some other conditions such as Takayasu arteritis, radiation injury, and congenital malformations [15] may affect the main renal artery. Atherosclerosis is a generalized progressive arterial disease associated with localized arterial occlusions that accounts for 90% of cases of renal artery stenosis. It usually involves the ostium and the proximal third of the main renal artery and perirenal aorta [15,16]. Arterial FMD is a non-inflammatory, nonatherosclerotic, occlusive condition of systemic arteries with predilection for renal and internal carotid arteries [19]. FMD of renal arteries is bilateral in nearly half of the patients, and more common on the right side (3:1); it is usually diagnosed in the fourth decade, is predominant in females, and most frequently affects the distal two thirds of the renal artery and its branches [15,16]. The exact incidence of FMD is not known due to a large number of asymptomatic cases; however, an autopsy study showed an incidence of 1% [9,12]. Intimal, medial, and adventitial FMD are three major pathologic subtypes of FMD. Although RCC is connected to hypertension and there are some suggestions that renal artery changes could be responsible for tumor necrosis in patients with RCC, the exact nature of this relationship is not fully understood. The aim of this study was to analyze morphometric parameters of renal arteries (longest diameter and thickness of arterial tunica media) in patients with RCC, to compare them with those of a control group of patients without RCC, and to gain additional, more objective information about the relationship between RCC and renal arteries.
Materials and methods We analyzed archival cases of RCC diagnosed at Ljudevit Jurak University, Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia,
in 2003. For these cases samples of renal arteries were also available. Of the consecutive series of 61 (M:F ¼ 38:23) cases, 21 (14 male and 8 female) cases were excluded because of the tangentially cut or artificially damaged renal artery specimens, especially in cases of right simple nephrectomy, when renal artery is cut at a length of 50–75%. The final sample consisted of 39 (M:F ¼ 24:15) RCC cases, patient age 35–74 years (mean 58.4 years). Tumor size ranged from 2–16 cm (mean 7.37 cm). All cases included in the study contained routinely sampled specimens of distal segments of renal artery, as well as renal vein and ureteral margin. The presence and extent of tumor necrosis were characterized using the degrees absent, less than 50% tumor necrosis, and using the degrees more than 50% tumor necrosis, as in similar studies of RCC [11] and studies of soft tissue-tumor grading [21]. The control group consisted of specimens from both renal arteries obtained during the 2004–2005 period from 16 (M:F ¼ 11:5) patients aged 32–85 years (mean 62.3 years) on routine autopsy at Ljudevit Jurak University, Department of Pathology, Sestre milosrdnice University Hospital, Zagreb, Croatia. Autopsy, as well as further histological analysis, did not disclose any malignant disease in the control group, and causes of death were non-tumor diseases (heart failure, pneumonia, and pulmonary thromboembolism). Measurements of renal arteries in the control group were performed on sections from 32 renal arteries. One block each from the distal and proximal parts was morphometrically analysed in all 32 renal arteries. FMD was classified into three principal pathological types: intimal, medial, and adventitial FMD [12]. Medial type (type II) was subdivided into three subtypes: medial ‘‘muscular’’ hyperplasia (type IIa), medial fibroplasia with aneurysms (type IIb), and perimedial fibroplasia (type IIc) [4,13,19,23]. Specimens from both groups of patients were equally processed; first routinely fixed in 10% buffered formaldehyde, embedded in paraffin, cut at 5 mm and stained with hematoxylin–eosin and orcein, and examined by light microscopy. Morphometric analysis of the longest diameter and thickness of renal artery tunica media on adequate sections was performed using a JVC TK-1270 video camera, Leica Diaplan microscope and Issa 3.1 computer software (Vamstek 2002, Zagreb, Croatia). The longest diameter was measured from adventitia to adventitia, and thickness of tunica media from elastica interna to elastica externa, using slides stained with orcein (Fig. 1A and B). In the group of patients with RCC, one bloc per case was evaluated, because after nephrectomy, only short distal segment of renal artery was available for histologic analysis. In both groups, we used 3 measurements per case and then counted the mean value.
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Fig. 1. Morphometric analysis of renal artery: (A) longest diameter, magnification 25; (B) thickness of tunica media, magnification 40; both microphotographs for morphometric analysis were stained with orcein.
Mann–Whitney U test was used for statistical analysis. The level of significance was set at po0.05.
Results In the study of 39 RCC cases, there were 24 (61.5%) male patients aged 38–74 years (mean 57.2 years) and 15 (38.5%) female patients aged 35–74 years (mean 53.6 years). Pathologic changes of renal arteries were found in 24 renal artery sections (M:F ¼ 12:12), whereas 15 (M:F ¼ 11:4) cases were free of pathologic changes of renal artery samples. Out of 24 cases with renal artery changes, renal artery atherosclerosis was recorded in 6 (M:F ¼ 4:2), and FMD in 18 (M:F ¼ 8:10) cases (Fig. 2A–C). Results of morphometric measurements of renal artery longest diameter and of tunica media thickness in the group of RCC patients are shown in Table 1. Statistical analysis yielded no significant differences in the longest diameter of renal artery or media layer thickness between the patients with (FMD or atherosclerosis) and without renal artery lesions (p ¼ 0.885 for diameter and p ¼ 0.828 for media thickness, p ¼ 0.213 for longest diameter and p ¼ 0.087 for media thickness). The comparison of cases with FMD and atherosclerotic changes in renal artery yielded no significant difference either (p ¼ 0.205 for longest diameter and p ¼ 0.096 for tunica media thickness). Tumor necrosis was found in 31 (79.5%) RCC cases, and of these, 23 (M:F ¼ 15:8) had less than 50% necrosis, and 8 (M:F ¼ 4:4) more than 50% of necrotic areas. Sections of renal arteries without tumor necrosis had a median diameter of 3492.27 mm (range 2757.30– 3852.82 mm) and a media thickness of 499.41 mm (range 353.37–643.03 mm). The median diameter of renal arteries with less than 50% of necrotic areas was
3448.18 mm (range 837.30–5248.28 mm), and tunica media thickness in these was 531.37 mm (range167.86–1153.30 mm). The median diameter of renal arteries with tumors containing more than 50% of necrotic areas was 4233.75 mm (range 2377.35– 5180.04 mm), with thickness of tunica media measuring 657.32 mm (range 365.45–969.52 mm). The comparison of diameter and thickness of tunica media of renal arteries from cases without necrosis with those with necrotic areas and between cases with different degrees of tumor necrosis produced no statistically significant differences (p40.05). In the control group, pathologic changes of renal arteries were found on 17 (53.1%) sections from proximal parts of renal arteries and on only 6 (18.8%) sections from distal segments of renal arteries. All changes observed on both distal and proximal sections were atherosclerotic, whereas FMD was not found at all. Measurements of distal and proximal sections in the control group are presented in Tables 2 and 3. Statistical analysis revealed no significant gender differences in renal artery diameter and tunica media thickness in either distal or proximal segments of renal arteries (p40.05). Within the control group, the comparison of renal artery diameter and tunica media thickness between sections without lesions and those with atherosclerosis yielded no statistical significance for either distal or proximal segments (p40.05). The longest diameter of distal segments of renal arteries in the control group was slightly wider when compared with renal arteries with RCC, but the difference did not reach statistical significance (p40.05). However, the comparison of tunica media thickness showed renal arteries from RCC cases to be significantly thicker when compared with distal segments of renal arteries in the control group (p ¼ 0.0002). The comparison of tunica media thickness between
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Fig. 2. (A) Macroscopic appearance of renal cell carcinoma with atherosclerotic lesions of renal artery, (B) microphotograph of a renal artery with fibromuscular dysplasia IIb, (C) microphotograph of a renal artery with atherosclerotic lesions; microphotographs were stained with hematoxylin and eosin, magnification 40.
Table 1. Median, minimum, and maximum values of measured parameters on renal arteries from cases with renal cell carcinoma
Table 2. Median, minimum, and maximum values of measured parameters on distal parts of renal arteries from control group
Median (mm)
Minimum (mm)
Median (mm)
3783.82 3808.79
837.30 859.95
5248.28 5203.66
3407.20 4154.71
837.30 3197.46
5214.47 5248.28
All
531.37
167.86
1153.30
No changes FMD ATH
503.61
167.86
969.52
529.34 622.63
353.37 520.73
1153.30 835.70
Diameter
Media layer thickness
All No changes FMD ATH
Maximum (mm)
All ¼ all cases with renal cell carcinoma; No changes ¼ cases of renal cell carcinoma without renal artery changes; FMD ¼ cases of renal cell carcinoma with fibromuscular dysplasia of renal arteries; ATH ¼ cases of renal cell carcinoma with atherosclerosis of renal arteries.
renal artery sections with atherosclerosis from the RCC group (median 622.63 mm) and distal sections with atherosclerosis from the control group (median 434.37 mm) yielded a statistically significant difference
Diameter
Media layer thickness
All 4109.88 No 4068.42 changes ATH 4237.82
Minimum (mm)
Maximum (mm)
2386.33 2386.33
7304.33 7304.33
3723.11
4821.75
All
386.30
171.19
651.28
No changes ATH
363.89
171.19
651.28
434.37
266.22
547.84
All ¼ all sections from distal segments of renal arteries; No changes ¼ sections from distal parts of renal arteries without pathological changes; ATH ¼ sections from distal parts of renal arteries with atherosclerotic lesions of renal arteries.
(p ¼ 0.019). A statistically significant difference was also found when tunica media thickness of sections without pathologic changes on renal arteries from the RCC group was compared with sections of distal parts without pathologic changes in the control group (p ¼ 0.010).
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Table 3. Median, minimum, and maximum values of measured parameters on proximal parts of renal arteries from control group Median (mm) Diameter
Media layer thickness
All 4999.14 No 4940.09 changes ATH 5052.17
Minimum (mm)
Maximum (mm)
2506.33 2765.93
9045.64 6757.04
2506.33
9045.64
All
368.22
138.31
721.66
No changes ATH
328.66
214.77
522.95
407.77
138.31
721.66
All ¼ all sections from proximal segments of renal arteries; No changes ¼ sections from proximal parts of renal arteries without pathological changes; ATH ¼ sections from proximal parts of renal arteries with atherosclerotic lesions of renal arteries.
Discussion Although both the present and previous studies [11,20] point to a high rate of renal artery lesions in RCC patients, we found no significant differences in renal artery diameter or media layer thickness between renal arteries without changes and those with FMD or atherosclerotic lesions. This finding was not unexpected since our study of the control group, as well as other studies [4,12,16,19], showed renal artery changes to be mostly segmental, with only a small part of renal artery being available for sampling and histological examination after radical nephrectomy due to RCC. However, when renal artery sections from the group of RCC patients were compared with distal segments of renal arteries from the control group, we found that tunica media was significantly thicker in the group of RCC patients. The difference in media layer thickness was also present when only sections with atherosclerosis from both groups were compared, as well as on comparison of sections without pathologic changes. These results suggest that renal arteries in RCC patients are changed, with a thicker tunica media that can narrow arterial lumina and influence arterial blood flow. According to some authors, necrosis in RCC is attributed to a decrease in microvessel density and immaturity of microvessels with the possibility that tumor necrosis is a consequence of acute hypoxia [10,17]. However, the exact pathogenesis of tumor necrosis as well as the cause and nature of renal artery changes, and the possible impact on tumor necrosis have not yet been fully clarified [11,17]. We observed an increase in media layer thickness in the group of RCC patients, with the presence and increased extent of
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tumor necrosis (no necrosis: less than 50% necrosis: more than 50% necrosis ¼ 499.4 mm, 531.4 mm, 657.3 mm); however, the differences were not statistically significant. Concerning a relatively small number of cases without tumor necrosis and a small number of cases with more than 50% tumor necrosis in the present study, the hypothesis that renal artery changes induce necrosis or influence the extent of tumor necrosis should be further analyzed (in larger series and in comparison with microvessel density). In the hypertensive population, high blood pressure is attributed mainly to atherosclerosis, whereas renovascular FMD is considered to be the cause of hypertension in less than 2% of patients [23]. In patients with renovascular hypertension, FMD is the underlying cause in 20%–50% of cases [12]. Hypertension has been implicated as a risk factor for the development of RCC, and also as a paraneoplastic manifestation of RCC [1,7,18]. Hypertension has also been implicated as a risk factor for increased mortality from RCC [5,8]. Due to the asymptomatic nature in a large number of cases and inadequately sensitive imaging methods, the true incidence and prevalence of FMD in the general, healthy population and in patients with hypertension or RCC remain unknown. The best method for detecting renal artery stenosis is digital subtraction angiography; however, the use of this method in daily routine is very rare, in particular in patients with renal tumor [14,22]. Based on our results, we may conclude that significantly thicker tunica media characterized renal arteries in the group of patients with RCC when compared with the control group, without any significant difference between arteries with and without pathologic changes. These findings suggest that renal arteries in all patients with RCC are changed, but since distribution of FMD and atherosclerosis could be only segmental, their presence may not be identified in all cases because whole renal artery is not available for pathologic examination due to operative techniques. Yet, it remains unknown whether they are the consequence of tumor or represent a risk factor for hypertension or even tumor growth. The morphometric results of our study encourage further studies to elucidate the cause of the high rate of renal artery lesions and the association of these lesions with the development and extent of tumor necrosis, as well as the exact relationship of the hypertension and RCC.
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